Gene flow

Gene duplication is a phenomenon in molecular genetics that involves the production of one or more copies of a gene. This process is a primary source of genetic variation that can lead to evolutionary innovation.

Overview

Gene duplication can occur through several mechanisms, including unequal crossing over, retrotransposition, chromosomal duplication, and genome duplication. The result is an extra copy of a gene, which can then evolve to take on new functions without disrupting the function of the original gene. This process is thought to have played a key role in the evolution of new gene functions and the complexity of genomes.

Mechanisms

Unequal Crossing Over

Unequal crossing over occurs during meiosis, when homologous chromosomes pair up and exchange genetic material. If the alignment of the chromosomes is not precise, one chromosome may end up with two copies of a gene, while the other has none.

Retrotransposition

Retrotransposition involves the creation of a cDNA copy of a gene, which is then inserted back into the genome at a different location. This can result in a new copy of the gene being created.

Chromosomal Duplication

Chromosomal duplication involves the duplication of an entire chromosome, resulting in two copies of all the genes on that chromosome. This can occur as a result of errors during cell division.

Genome Duplication

Genome duplication, also known as polyploidy, involves the duplication of the entire genome. This can occur as a result of errors during cell division, or as a result of hybridization between species.

Evolutionary Significance

Gene duplication is thought to be a major driver of evolutionary innovation. The extra copy of a gene can evolve to take on new functions, while the original gene continues to perform its original function. This can lead to the evolution of new proteins and metabolic pathways, and can contribute to the complexity of genomes.

See Also

• Genetic recombination
• Genetic variation
• Molecular evolution

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  Gene flow diagram

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  Modes of speciation

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  Marine iguana